'Electrical disturbance' causes third Diablo Canyon shutdown in three years

HAT TRICK: For the third year in a row, the Unit 2 reactor at Diablo Canyon underwent an automatic shutdown due to an electrical disturbance.

The Unit 2 reactor at Diablo Canyon nuclear power plant automatically shut down on Feb. 2 after an “electrical disturbance” resulted in a “flashover event,” the third such occurrence in as many years.

The exact cause is under investigation, but a preliminary investigation revealed that moisture and dust accumulated on a lightning arrestor, causing a disruption in the flow of electricity coming out of the plant, said PG&E spokesman Blair Jones.

“The plant performed as it was designed to do,” Jones said. “Once the sensitive equipment detected this disturbance, it shut down to protect itself.

This makes the third year in a row such an event has led to an automatic shutdown. On Oct. 11, 2012, as well as July 10, 2013, Unit 2 shut down because of electrical disturbances. The 2013 flashover occurred as crews were washing down the equipment.

Once the cause of the most recent shutdown is fully investigated, PG&E will replace the equipment and bring the plant back up to full power.